Scanning device



Feb. 24, 1953 w. M. CADY ET AL SCANNING DEVICE Filed March 5, 1946 SECTION C-C FIG. 4

INVENTOR. NICHINSON SECTION 5-5 FIG. 3

DAVID B. WILLOUGHBY .M. CADY ATTORNEY Patented Feb. 24, 1953 UNITED STATES PATENT .SCANNINGDEVIGE 'Willoughby M. Carly, Cambridgc,an'd"David B.

Nichinson,

Brookline, Mass.,

as'signors, by

'mesne assignments, to the United 'Statesof America asrepresented' by the Secretary of the Navy .Aphlication' March 5, 1946;:SeriaLNoJ652J99 This invention relates to a means f for 'controlling'the tilt motion of rotating or oscillating'antennas. More particularlyit relates'tto an'electromagnetio ratchet means for 'controlling'the tilt mechanism ofthe antenna'without the use of s'lipringsgpush-tubes, ora secondary power source.

In the mechanical control of parabolic and other antennas a'necessary feature is a means'of controlling the tilt of the "antenna. Tilt control has been mechanized by (1) 'a'motor and gear train on the scannenba'se'which slides'a thrust bearing along'the'scanner'axis, thus actuating a linkage mounted on the'moving portion of the .scanner and thereby causing the reflector to tilt; 'or'('2) feeding power'through slip rings to a'small 'electric motor which'drivesagear train and link- ;age. mounted on the moving portion ofthe "scanfiner. "'The present invention avoids both of these complex methods.

Accordingly, .itis an object of this invention to provide a tilt control for moving antennas.

Another object'of this invention is to provide a 'tilt control which will have a small number of parts 'on the moving portion of theantenna mount.

"Another'object of this invention is toprovide a tilt control which will operate from the primary "power source usedto rotate the antenna.

These and further'objects will become more readily-apparent upon'consideration'of the following description and the accompanying drawings-of which:

"Fig. '1 is a sectional plan view 'ofan embodiment of the invention taken'at AA;

' Fig-2 ls'a "front elevation" view'ofithisembodiment;

Fig. '3 isa sectional view'taken' atfB-B; Fig. '4 is *a sectional view taken at C-"C. In the operation of a scanning-antennae refiectori is rapidly oscillated about a :torque :tube 4 axis, and tilt adjustmentiof the-reflector is cle- Jsirable during ioperation. Half-wave rectification -:of "this roscillatory moton :with a coil-actu- -ated ratchet as explained hereinafter presents a rapid-intermittent motion which is satisfactory for tilt adjustment. Introduction of a second suchratchetpermits the choice in direction of the adjustment. In operation .a gear on the torque tube isfixed in motion. everyalternate half cycle relative-tothemount,.and,this causes movement of the tilt g'earing-and consequenttilting of the reflector. The operationmaybe'iurther explained byrreferenceto the accompanying drawings. Torque tube or shaft of rotationltl'is roattached to shaft l3. "gear 14, is mounted on friction plate 22jand is held by" friction ring 23. Friction ring 23in turn is'held to torque tube lfiby retaining"ring"24. .Electromagnetic'relay -ratchets 25 and "26 are through shaft 13 to worm -29. worm gear 39 in response to motion'of gear-l4. Section'-BB given in Fig. 3 shows that tilt crank '3 I is attachedto-"shaft- 32--whichbears worm" gear 39. 'Tilt crank 3E connects to tilt pivotplate 33 plate 22.

'tatably mounted in a suitable bearing'on the scan- "nerbase II in any conventionarmanner. Turntable l9 'supports'reflector '20 andis mounted on torque tube ill. Arm [2 Ofturntable-I9holds shaft l3 inbearingQl. "Spur gear-M is*rigidly Spur gear l5 engagesspur mounted on'scanner base H and engage gear 15 with shoes Hand 23' respectively. Shoes 21-"and 23'a1e made of wear resistant metal and "are-so inclined relative to the spur gear teeth that" they will lock'the 'spurgearin one directionandwill slide on the gear teeth 'in the other "direction.

".The diametral' pitchof spur gear I 5 must be great "enough "that the narrowest sector of antenna oscillation will-still include-a sufficient numberof teethto give'tilt motion Wheneithershoe-2'l-or 28-engages gear 15. Gear-l4 transmits motion Worm 29 moves through lever 'arm '34. Section C-C given'in Fig.4 shows the structure by which the motion of plate 33 i is transmitted 'to reflector 26. Tilt pivot'plate 33 is'attachedto tilt pivot flange 36 "which is keyed-to shaft 3'! byWoodru'ff key '33.

Spring 35 prevents'any' backlash in antenna motion. Bearing 39*is attached toturntable it by :means not shownand carries "shaft -37 "and'its tem disclosed motion'ofgear IL! is transmitted to "reflector '20.

"torque "tube associated components. Bythe mechanical sys- For purposes of demonstration, IE "will be assumed to oscillate through approximately A phantom view of a position near the limit of oscillation hasbeen shown in dotted lines in Fig. 1. In the condition when actuating coil I 8 is de energize'd ratchet arm I? is pushed out by clockwise rotation of gear i5 which will revolve with torquetube ll! due to the friction established by ring 23 and In this case, it isreadily evident'that no relative motionwill occur between'ge'ars I4 and l5since they both'revolve with torquetube 1G. Whenactuating coil i8 is energized'however, ratchet arm'l 1' causes shoe ZB'to engagegear i5 and during the counterclockwise motion of torque tube It, gear liiwillrevolvewithrespect to torque'tube I 8, since gear I5 is now'fixed in motion relative to scamier base l'l. "Since gear "It is mounted on arm i2 and must assume the phantom position, relative motion occurs between gears l4 and I5. This motion is then translated via shaft I3 to the aforementioned linkage for tilting the reflector 20 which is undergoing the same angular motion as arm l2 which houses shaft I 3 since both reflector 20 and arm I2 are on turntable I9. On the clockwise return motion ratchet arm I1 is pushed out by the rotation of gear l which results from the friction established by ring 23 and plate 22. In this manner, a rapid intermittent motion is provided which is entirely satisfactory for tilt adjustment. It is readily seen that a slow sinusoidal tilt motion will result if one ratchet is continually engaged. This is due to the fact that tilt crank 3| is essentially a point on the circumference of a disc of motion. Consequently as this point is rotated its incremental linear displacement relative to a plane tangent to the circle will be less for a given angular displacement as the point falls closer to the tangent plane. It is obvious that return tilt motion of the reflector is provided by the action of electromagnetic ratchet 25 which causes shoe 2! to engage gear 15. Thus two-directional tilt control is established.

The foregoing description has presented an explanation of this invention in the particular application of an electromagnetic ratchet for tilt control, but the principles of this invention are of broader application in ways which will be apparent to those skilled in the art. It will be understood that the above-disclosed embodiment is primarily illustrative and that the invention includes such embodiments as fairly come with the spirit and scope of the appended claims.

What is claimed is:

1. A mechanical structure for tilt control of moving antennas including, two electromagnetically controlled ratchets, driving means, a shaft of rotation actuated by said driving means, an antenna turntable mounted on said shaft of rotation, an antenna reflector mounted on said turntable, a first gear freely mounted on said shaft of rotation and which may be locked against rotation with said shaft by said ratchets, a second gear mounted on said turntable and engaging said first gear, a mechanical linkage connecting said second gear and said antenna reflector, wherein said structure utilizes the power source of azimuth movement of said antenna turntable to yield tilt motion of said reflector upon locking of said first gear against rotation.

2. An electromagnetic ratchet antenna tilt control structure comprising, a torque tube, a turntable mounted on the end of said torque tube, a scanner base, an antenna reflector mounted on said turntable, a first spur gear freely mounted on said torque tube, a friction plate and a friction ring so mounted around said gear on said torque tube that said gear will rotate with said torque tube unless subject to external force, a second spur gear which engages said first gear, a shaft mounted in a suitable bearing in said turntable wherein said shaft has pinned to it said second gear, a worm mounted on said turntable and driven by said shaft, a worm gear mounted on said turntable and driven by said worm, a second shaft which is pinned to said worm gear, a crank arm attached to said second shaft, a lever arm connected to said crank arm, a third shaft used as tilt axis for said reflector connected to said reflector and mounted in a suitable bearing on said turntable, a tilt pivot plate connected to said third shaft and to said lever arm, first and second electromagnetically controlled ratchets mounted on said scanner base so that the lever arm of said first ratchet engages said first gear in one direction of rotation and the lever arm at said second ratchet engages said first gear in the opposite direction of rotation wherein said structure provides a tilt control for said reflector which utilizes the power source of antenna oscillation and which is electromagnetically controlled.

3. A mechanical structure for the tilt control of an antenna comprising a driven torque tube, electromagnetically controlled ratchets, an antenna turntable mounted on said torque tube, an antenna reflector mounted on said turntable, a gear freely mounted on said torque tube and fixable against rotation with said torque tube by said ratchets, and a mechanical linkage connecting said gear and said antenna reflector for providing tilt control of said antenna. reflector in response to said ratchets.

4. An antenna orientation control structure comprising, a turntable for supporting said antenna, a driven torque member fixedly attached to said turntable for causing said antenna to scan in a horizontal plane, means attached to said turntable for causing said antenna to scan in a vertical plane, a first gear freely mounted on said torque member, friction means for locking said first gear to said torque member, a second gear in mesh with said first gear and carried by said turntable, means connecting said second gear to said vertical scanning means, and means for intermittently locking said first gear against rotation with said torque member, whereby said vertical scanning means is actuated in response to rotation of said turntable.

5. An antenna orientation control structure comprising, a turntable for supporting said an tenna, a driven torque member fixedly attached to said turntable for rotating said turntable to cause said antenna to scan in a horizontal plane, a first gear freely mounted on said torque member, a friction ring disposed between said torque member and said first gear for retaining said first gear in rotation with said torque member, ratchets for periodically engaging and locking said first gear against rotation with said torque member, means attached to said turntable for causing said antenna to scan in a vertical plane, a second gear in mesh with said first gear and connected to said last-mentioned means, locking of said first gear by said ratchets causing rotation of said second gear relative thereto during rotation of said turntable, said second gear actuating said last-mentioned means during periods of locking of said first gear.

6. An antenna orientation control structure comprising, a turntable for supporting said antenna, a driven torque member fixedly attached to said turntable for rotating said turntable to cause said antenna to scan in a horizontal plane, a first gear freely mounted on said torque member, a friction ring disposed between said torque member and said first gear for retaining said first gear in rotation with said torque member, ratchets for periodically engaging and locking said first gear against rotation with said torque member, a second gear in mesh with said first gear and carried on said turntable, locking of said first gear causing rotation of said second gear relative thereto during rotation of said turntable, a shaft attached to said second gear and rotatable therewith, a worm mounted on said shaft, a worm gear driven by said worm, and a bell crank driven by said worm gear and attached to said antenna to cause vertical scanning thereof.

7. An antenna orientation control structure comprising, a turntable for supporting said antenna, a driven torque member fixedly attached to said turntable for rotating said turntable to cause said antenna to scan in a horizontal plane, a first gear freely mounted on said torque member, a friction ring disposed between said torque member and said first gear for retaining said first gear in rotation with said torque member, a first electromagnetically controlled ratchet for arresting motion of said gear in one direction and locking of said first gear against continued rotation with said torque member, a second electromagnetically controlled ratchet for arresting motion of said first gear in a second direction and locking said first gear against continued rotation with said torque member, a shaft mounted on said turntable, a second gear carried by said shaft and in mesh with said first gear, said second gear being rotatable in response to rotation of said turntable only during periods of locking of said first gear, and a gear train and crank arm driven by said second gear for causing vertical scanning of said antenna.

8. An antenna orientation control structure comprising a turntable for supporting said antenna, a driven torque tube fixedly attached to said turntable for causing said antenna to scan in a horizontal plane, means attached to said turntable for causing said antenna to scan in a vertical plane, means mounted on said torque tube and connected to said vertical scanning means, and means for locking said last-mentioned means to impart power to said vertical scanning means from said torque tube.

9. An antenna orientation control structure comprising a turntable for supporting said antenna, a driven torque tube fixedly attached to said turntable for causing said antenna to scan in a horizontal plane, means attached to said turntable for causing said antenna to scan in a vertical plane, power transmitting means mounted on said torque tube and connected to said vertical scanning means, and means for locking said power transmitting means to impart power to said vertical scanning means from said torque tube.

WILLOUGI-IBY M. CADY. DAVID B. NICHINSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,407,310 Lundy et al Sept. 10, 1946 2,410,827 Langstroth et a1. Nov. 12, 1946 

